# Chapter 7 Descriptive Syntax in R.

# Read in Dental Veneer Data and attach to working memory.
veneer <- read.delim("veneer.dat.txt", h = T)


# Define age, time and tooth factors. 
age.f <- factor(veneer$age)
time.f <- factor(veneer$time)
tooth.f <- ordered(veneer$tooth)

 
veneerf <- data.frame(veneer,age.f, time.f, tooth.f)

# Sort the age factor in ascending order. 
# sort(age.f)

library(lattice)  # Load the library for trellis graphics.
trellis.device(color=F) # Make sure color is turned off.
 
# Load the nlme library, which is required for the 
# plots below as well as for subsequent models.
library(nlme)
 
veneer.g1 <- groupedData(gcf ~ time | tooth.f, outer = ~ age.f, data = veneerf)

plot(veneer.g1, display = "tooth", outer = TRUE, aspect = 2, key = F, xlab = "time", ylab = "GCF", main="age" ,
layout=c(4,3))